Hydrocarbon (HC) vapors may emanate from the interior of an engine and escape through the engine's intake system. Therefore, HC traps are used in internal combustion engines to capture hydrocarbon vapors which may be otherwise leaked into the environment surrounding the engine. HC traps therefore reduce emissions (e.g., evaporative emission) from the engine.
US 2005/0145224 discloses an evaporative emission storage device having HC adsorption/desorption material positioned between porous polymeric layers. Hydrocarbon vapors may flow through the porous polymeric layers and into the HC adsorption/desorption material where the vapor is stored. The Inventors have recognized several drawbacks with the evaporative emission storage device disclosed in US 2005/0145224. Firstly, filling the area between the porous polymeric layers with adsorption material may involve a complicated and costly manufacturing process, increasing the cost of the vehicle. Additionally, the polymeric layers surrounding the adsorption material may limit the flow rate of the HC vapor into and/or out of the adsorption material. As a result, the amount of HC vapors captured by the storage device may be reduced, which may increase emissions (e.g., evaporative emissions). Furthermore, the profile of the HC trap may be increased when the polymeric material is used to enclose adsorption material. Still further, it may be difficult to provide a desired amount of rigidity to the storage device via the porous polymeric layers while at the same time providing the desired adsorption and/or desorption rate of the HC vapor in the storage device. Therefore, tradeoffs between desired characteristic in the storage device disclosed in US 2005/0145224 may be necessitated.
The Inventors herein have recognized the above issues and developed a hydrocarbon (HC) trap for an intake system of an engine. The HC trap includes a stack of consecutively layered polymeric sheets at least a portion of the sheets impregnated with a HC vapor adsorption/desorption material, the stack of sheets extending from a first exterior surface to a second exterior surface.
The polymeric sheets serve multiple uses, providing structural integrity to the HC trap and providing HC adsorption via the adsorption/desorption material embedded within the sheets. Consequently, the adsorption and/or desorption rate of HC vapors in the HC trap may be increased when HC adsorption material is integrated into the polymeric sheets. Moreover, the profile of the HC trap may be reduced, if desired, when the sheets provide both structural integrity as well as adsorption/desorption functionality. Furthermore, the cost of the HC trap may be reduced when the polymeric sheets serve multiple purposes.
In one example, there may be no intervening adsorption/desorption material positioned between the sheets, such as carbon pellets. In this way, the cost of the HC trap may be reduced via a reduction in materials in the trap. It will be appreciated that the manufacturing cost of the HC trap may be reduced when the sheets are impregnated with HC vapor adsorption/desorption material and there is no adsorption/desorption material positioned between the sheets, due to the elimination of a step of filling the area between the sheets with loose adsorption/desorption material.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.